By: Fabiola Grosshan
Submitted: 2010-07-05 01:39:20 | Word Count: 604
Troubleshooting strange noises that occur in your BMW can go a long ways to helping you identify problems early on and get them repaired before they worsen. The best way to listen for noises is with a stethoscope. It’s easy to place it in the spot you want and it provides you with the most accurate sound. Here are some basic guidelines for troubleshooting some of the most common problem sounds on your BMW.
Bangs
If you hear a sharp bang in your car’s engine, something that sounds like a rifle shot, you’re probably dealing with engine backfire. This could be caused by a leak that’s creating a rich air/fuel mix, or it could be related to a clogged monolithic converter. The bang will appear once and it will precede a significance increase in power.
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Buzzing
An annoying buzz sound usually means there’s some bad positioning of the car’s interior trim parts. Have someone drive the car while you look around the interior for the source of the noise. Luckily this sound does not usually signal serious issues.
Loud clangs and clacks
This is a sound that could not be emitted by any small, light parts. It’s definitely coming from a heavy and likely important component of the vehicle. Such a sound could be coming from a set of gears, or a bad rear axle pinion bearing, which will make the sound when you shift into driver or reverse.
Grinding
This is usually a loud, unpleasant sound reminiscent of a dentist’s drill. If you hear it coming out of your BMW, it means something real bad is happening, and it’s happening fast. It’s often related to break issues, and it can mean that the linings of your BMW are out or that you have an overly aggressive friction material formula eating away at your rotors.
Hissing
A continuous hissing sound that fluctuates along with your rpm could mean a couple of things. It could be related to normal belt noise, in which case it’s not a problem or it will require a minor check up. It could also be related to a leak in the BMW’s cooling system. Using a black light will make finding a leak easier.
Knock
This is a deep, hollow sound, like the sound of someone knocking on a wooden door. It’s usually a sign that an important component is failing and is in immediate need of repair. Unfortunately, determining what the sound is related to can be a bit difficult, since a loose pin makes the noise just as well as a failed rod bearing. To determine the cause, you’ll want to check the idle oil pressure. If it’s low, the problem is likely the bearings. Now, listen with a stethoscope. If it’s a faulty rod bearing, the sound will come more from the oil pan; if it’s a wrist pin, the sound will come more from the water jacket. Next, hold the BMW’s RPM meter at 2500 and jerk the throttle open and let it shut close. This procedure will increase the sound if it’s a faulty rod. If the sound doesn’t increase, chances are it’s a pin. If you know what to look for, you can also try visually inspecting the pan.
Whir
You’re BMW will make a whirring sound sometimes that just means the engine and all the mechanical components are working just fine. This is one of the few sounds that you usually don’t have to worry much about.
